Modular exhaust tube system

ABSTRACT

A modular exhaust tube system for directing exhaust gases from an internal combustion engine. The exhaust tube system includes first and second elongate half-shells, with each half-shell comprising an elongate thin-wall body having a substantially U-shaped cross-sectional profile with a constant sideways opening along the length of the body. The exhaust tube system also includes a center brace having dimensions which span the length and height of the sideways openings. The sideways openings of the first and second half-shells are coupled together around the center brace to form a flattened elongate exhaust tube having an inlet end and an outlet end for directing exhaust gases from the internal combustion engine. In one aspect the first and second half-shells are selected from a group of interchangeable and modular half-shells having different substantially U-shaped cross-sectional profiles that are reversible top-to-bottom and end-to-end.

FIELD OF THE INVENTION

The field of the invention is generally related to exhaust systems forautomobiles, and more specifically to exhaust tube systems configured toincrease the ground clearance on race cars used on oval tracks.

BACKGROUND OF THE INVENTION AND RELATED ART

Race cars used in automobile racing are typically constructed such thatonly a minimal amount of clearance is maintained between the undersideof the car and the surface of the roadway or track. This is done tolower the center of gravity of the vehicle to improve vehicle handlingand resistance to rolling over, and to minimize the drag on the car dueto the air passing underneath. Such race cars typically have very stiffsuspension systems which do not allow the vehicle to travel as great adistance up and down nor side-to-side as a standard production car, thusallowing for a reduced ground clearance. However, one of the challengesencountered in lowering the race car closer to the race track isproviding sufficient clearance for the vehicle exhaust system, which isone of the lowest hanging components of a typical car, including racecars.

This problem is particularly acute on cars which race on oval racetracks, such as stock cars. The exhaust pipes of stock cars typicallyexit toward one or both sides of the car so as to minimize the length ofthe exhaust pipes and the resulting exhaust gas back pressure whichlowers engine power output and overall engine performance. As such, theminimum ground clearance of the exhaust system often occurs where theexhaust pipes cross under the longitudinally-extending main framemembers of the chassis at the sides of the vehicle. Stock cars typicallyrace on oval tracks in a counter-clockwise rotational direction withcentrifugal force causing the body and chassis of the car to lean towardthe outside of the turn, or toward the right or passenger side of thecar. Thus, the ground clearance on the right side of the car is usuallyless than the left side during cornering. Moreover, banked tracks canalso induce high downward loads to the suspension system of stock carsrequiring additional ground clearance.

SUMMARY OF THE INVENTION

As broadly described herein, a representative embodiment of the presentinvention includes a modular exhaust tube system for directing exhaustgases from an internal combustion engine. The exhaust tube systemincludes first and second elongate half-shells, with each half-shellcomprising an elongate thin-wall body having a substantially U-shapedcross-sectional profile with a constant sideways opening along thelength of the body. The exhaust tube system also includes a center bracehaving dimensions which span the length and height of the sidewaysopenings. The sideways openings of the first and second half-shells arecoupled together around the center brace to form an enclosed andflattened elongate exhaust tube having an inlet end and an outlet endfor directing exhaust gases from the internal combustion engine. In oneaspect the first and second half-shells are selected from a group ofinterchangeable and modular half-shells having different substantiallyU-shaped cross-sectional profiles that are reversible top-to-bottom andend-to-end.

As broadly described herein, another representative embodiment of thepresent invention resides in an exhaust tube system for directingexhaust gases from an internal combustion engine, and which includesfirst and second elongate half-shells, each half-shell comprising anelongate thin-wall body having a substantially U-shaped cross-sectionalprofile with a constant sideways opening along the length of the body,and with both a top edge and a bottom edge of the sideways opening beingformed with an inwardly-bending lip. The exhaust tube system alsoincludes a center brace having dimensions which span the length andheight of the sideways openings. The sideways openings of the first andsecond half-shells are coupled together around the center brace to forman enclosed and flattened elongate exhaust tube having an inlet end andan outlet end for directing exhaust gases from an internal combustionengine, and with the inwardly-bending lips of the coupled half-shellsjoining together around the center brace to form a top groove and abottom groove for containing weld melt from a linear weld.

The present invention also includes a method for making an exhaust tubesystem for an internal combustion engine, which method includesobtaining first and second elongate half-shells, with each half-shellcomprising an elongate thin-wall body having a substantially U-shapedcross-sectional profile with a constant sideways opening along thelength of the body. The method also includes obtaining a center bracehaving dimensions which span the length and height of the sidewaysopenings. The method further includes aligning the sideways openings ofthe first and second half-shells together around the center brace, andcoupling the half-shells and the center brace together to form anenclosed and flattened elongate exhaust tube having an inlet end and anoutlet end for directing exhaust gases from an internal combustionengine.

BRIEF DESCRIPTION OF THE DRAWINGS

Features and advantages of the present invention will be apparent fromthe detailed description that follows, and when taken in conjunctionwith the accompanying drawings together illustrate, by way of example,features of the invention. It will be readily appreciated that thesedrawings merely depict representative embodiments of the presentinvention and are not to be considered limiting of its scope, and thatthe components of the invention, as generally described and illustratedin the figures herein, could be arranged and designed in a variety ofdifferent configurations. Nonetheless, the present invention will bedescribed and explained with additional specificity and detail throughthe use of the accompanying drawings, in which:

FIGS. 1A-1B together illustrate perspective exploded and assembled viewsof a modular exhaust piping system, in accordance with a representativeembodiment of the present invention;

FIGS. 2A-2E together illustrate a group of modular elongate half shells,in accordance with a representative embodiment of the present invention;

FIGS. 3A-3E together illustrate a group of modular center braces, inaccordance with a representative embodiment of the present invention;

FIGS. 4A-4D together illustrate the reversibility of two identicalmodular elongate half shells from the group of FIGS. 2A-2E;

FIGS. 5A-5J together illustrate the interchangeability within the groupof modular elongate half shells from the group of FIGS. 2A-2E;

FIGS. 6A and 6B together illustrate the inwardly-bending lips of coupledhalf-shells joined together to form grooves for containing weld melt, inaccordance with a representative embodiment of the present invention;

FIGS. 7A and 7B together illustrate perspective exploded and assembledviews of a modular exhaust tube system, in accordance with anotherrepresentative embodiment of the present invention;

FIGS. 8A and 8B together illustrate perspective exploded and assembledviews of a modular exhaust tube system, in accordance with yet anotherrepresentative embodiment of the present invention;

FIGS. 9A and 9B together illustrate perspective exploded and assembledviews of a modular exhaust tube system, in accordance with yet anotherrepresentative embodiment of the present invention;

FIGS. 10A-10E together illustrate an exhaust system having a pair ofmodular exhaust tubes orientated as a tandem pair, in accordance withanother representative embodiment of the present invention;

FIGS. 11A-11B together illustrate side and bottom views of a racing carhaving a tandem pair of modular exhaust tubes, in accordance with arepresentative embodiment of the present invention; and

FIGS. 12A-12B together illustrate side and bottom views of a racing carhaving a separated pair of modular exhaust tubes, in accordance with arepresentative embodiment of the present invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The following detailed description makes reference to the accompanyingdrawings, which form a part thereof and in which are shown, by way ofillustration, various representative embodiments in which the inventioncan be practiced. While these embodiments are described in sufficientdetail to enable those skilled in the art to practice the invention, itshould be understood that other embodiments can be realized and thatvarious changes can be made without departing from the spirit and scopeof the present invention. As such, the following detailed description isnot intended to limit the scope of the invention as it is claimed, butrather is presented for purposes of illustration, to describe thefeatures and characteristics of the representative embodiments, and tosufficiently enable one skilled in the art to practice the invention.Accordingly, the scope of the present invention is to be defined solelyby the appended claims.

Furthermore, the following detailed description and representativeembodiments of the invention will best be understood with reference tothe accompanying drawings, wherein the elements and features of theembodiments are designated by numerals throughout.

Illustrated in FIGS. 1-12 are several representative embodiments of amodular exhaust tube system for directing exhaust gases from an internalcombustion engine, which embodiments also include various methods formaking or assembling an exhaust tube from the modular exhaust tubesystem components. As described herein, the modular exhaust tube systemof the present invention provides several significant advantages andbenefits over other types of exhaust systems. However, the recitedadvantages are not meant to be limiting in any way, as one skilled inthe art will appreciate that other advantages may also be realized uponpracticing the present invention.

Illustrated in FIGS. 1A and 1B are perspective exploded and assembledviews of a modular exhaust tube 10 in accordance with a representativeembodiment of the present invention. The exhaust tube 10 includes firstand second half-shells 20, and more specifically a first elongatehalf-shell 32 and a second elongate half-shell 34, with each half-shellfurther comprising an elongate thin-wall body 36 having a substantiallyU-shaped cross-sectional profile with a constant sideways opening 38along the length of the body. The assembled exhaust tube 10 alsoincludes a center brace 60 having dimensions which span the length 42and height 44 of the sideways openings. The respective sideways openings38 of the first and second half-shells 20 are similarly shaped and sizedto mate and be coupled together around the center brace 60 to form aflattened elongate exhaust tube 10 having an inlet end 12 and an outletend 14 for directing exhaust gases from an internal combustion engine.In one aspect of the invention both of the first and second half-shellsand the center brace can be made from a mild carbon steel, such as ASTM1008 or ASTM 1018 steel, etc., that is suitable for most machiningoperations such as bending, punching, welding, and grinding, etc. Theraw metal stock for the various components can come in sheets having athickness between 1/16 inch and ⅛ inch, with a nominal thickness ofabout 3/32 inch.

As shown in FIGS. 2A-2E, the first 32 and second 34 elongate half-shellsof the modular exhaust tube system can be selected from a group ofinterchangeable and modular half-shells having elongate thin-wall bodies36 with different substantially U-shaped cross-sectional profiles. Forinstance, the two “curved” half-shells 20 illustrated in FIG. 2A caneach have a substantially similar U-shaped cross-sectional profile thatis shaped much like a sideways “U”, with a smoothly curved and roundedside and an open opposite side forming the sideways opening 38 along thelength of the body. Alternatively, the two “rectangle” half-shells 22illustrated in FIG. 2B can have a substantially U-shaped cross-sectionalprofile that is more rectangular with a squared-off side having sharp 90degree corners. The substantially U-shaped cross-sectional profile ofthe two “trapezoid” half-shells 24 illustrated in FIG. 2C can have atrapezoid-shaped profile with one of the top and bottom pieces beingwider than the other and with an angled side. Furthermore, the two“sigma” half-shells 26 illustrated in FIG. 2D can have a sigma-shapedprofile to form a side having an inwardly-directed peak, while the two“peaked” half-shells 28 illustrated in FIG. 2E can have a peak-shapedprofile to form a side having an outwardly-directed peak. As will bedescribed in more detail below, and as shown in FIG. 10E, the angles ofthe inwardly-directed peak of the sigma half-shells 26 can match theangles of the outwardly-directed peak of the peak half-shells 28, sothat the sides of the two half-shells can be positioned substantiallyadjacent to each other to form an angled gap with constant spacingbetween the sides.

It is to be appreciated that other complimentary shapes for thesubstantially U-shaped cross-sectional profiles of the elongate halfshells, as may be contemplated by one of skill in the art but notspecifically illustrated herein, are also considered to fall within thescope of the present invention.

As illustrated in FIGS. 3A-3E, the center brace of the modular exhausttube system can also be selected from a group of interchangeable andmodular center braces having various aperture configurations along thelength 82 thereof. For instance, the center brace 60 illustrated in FIG.3A can have a plurality of round apertures 72 formed along its lengthfor allowing the exhaust gases to pass from one side to the other afterassembly with two half-shells into the flattened elongate exhaust tube10, as shown in FIG. 1B. Alternatively, the center brace 62 shown inFIG. 3B can be solid along the length thereof to restrict the exhaustgases from passing from one side to the other in the enclosed exhausttube. The center brace 64 shown in FIG. 3C can have NACA duct-shapedapertures 74 formed along a length thereof. A NACA duct aperture is agenerally triangular opening have its apex pointed against the directionof flow and with curved sides configured to create opposing vortexeswhich help to direct the flow through the aperture. Additionally, centerbrace 66 shown in FIG. 3D can have oblong or elliptical apertures 76with the long axis of the apertures aligned with the length of theexhaust tube, while center brace 68 shown in FIG. 3E can have roundedslot-shaped apertures 78, or rectangular slots with rounded ends, alsowith the long axis of the slots aligned with the length of the exhausttube.

It is to be understood that the shapes of the apertures formed throughthe center braces illustrated in FIGS. 3A and 3C-3E serve to illustratea few representative embodiments of the center braces, and that otheraperture shapes, such as triangular and polygonal shapes, etc., are alsopossible and can be considered to fall within the scope of the presentinvention.

In another representative embodiment of the modular exhaust tube system,any of the half-shells illustrated in FIGS. 2A-2E can be reversibletop-to-bottom. For instance, either of the first 32 or second 34trapezoidal half-shells 24 of FIG. 2C can be reversed top-to-bottom, asshown in FIGS. 4A-4C. In FIG. 4A, for example, the first 32 and second34 half-shells are in the same orientation as in FIG. 2C, with the shortsegment on top and the longer segment on the bottom. In FIG. 4B, firsthalf-shell 32 has been reversed top-to-bottom so that the longer segmentis on the top and the shorter segment is on the bottom, while the secondhalf-shell 34 remains in the same orientation as shown in FIG. 4A.Likewise, in FIG. 4C the first half-shell 32 can remain fixed in theorientation shown in FIG. 4A while the second half-shell 34 can bereversed. And as shown in FIG. 4C, both the first 32 and second 34half-shells can be reversed top-to-bottom. It is to be appreciated thateach of the other half-shell shapes shown in FIGS. 2A, 2B, 2D, and 2Ecan also be reversible top-to-bottom in a similar fashion.

Each of the different half-shells illustrated in FIGS. 2A-2E can beconfigured with a similarly shaped and sized sideways opening 38 alongthe length thereof, so that any two half-shells selected from the groupof half-shells having a different substantially U-shaped profile can bemixed and matched together to form the flattened elongate exhaust tube10. Thus, illustrated in FIGS. 5A-5J are various permutations of theassembled elongate exhaust tube 10 which can be constructed using thedifferently-shaped half-shells of the modular exhaust tube systemdescribed above. It is to be appreciated that each half-shell can alsobe reversible end-to-end, so that a half-shell of any shape can occupyeither of the arbitrary first 32 or second 34 half-shell positions.Thus, illustrated in FIG. 5A are the principle and reversed combinationsof a trapezoid half-shell joined to a curved half-shell. In FIG. 5B areshown the principle and reversed combinations of a trapezoid half-shelljoined to a sigma half-shell. In FIG. 5C are shown the principle andreversed combinations of a trapezoid half-shell joined to a rectanglehalf-shell. In FIG. 5D are shown the principle and reversed combinationsof a trapezoidal half-shell joined to a peaked half-shell. In FIG. 5Eare shown the principle and reversed combinations of a curved half-shelljoined to a sigma half-shell. In FIG. 5F are shown the principle andreversed combinations of a curved half-shell joined to a rectanglehalf-shell. In FIG. 5G are shown the principle and reversed combinationsof a curved half-shell joined to a peaked half-shell. In FIG. 5H areshown the principle and reversed combinations of a rectangle half-shelland a sigma half-shell. In FIG. 5I are shown the principle and reversedcombinations of a rectangle half-shell joined to a peaked half-shell.And in FIG. 5J are shown the principle and reversed combinations of asigma half-shell joined to a peaked half-shell.

Again, it is to be appreciated that other complimentary shapes for thesubstantially U-shaped elongate half shells not illustrated herein cannevertheless be considered to fall within the scope of the presentinvention.

Each of the elongate half-shells 32, 34 having a substantially U-shapedcross-sectional profile with a constant sideways opening along thelength of the thin-wall body can be formed by bending or folding theidentically-sized piece of sheet steel into the various differentshapes. Therefore, despite the differences in the shapes of theirenclosed ends and cross-sectional areas, each of the differently-shapedhalf-shells can have the same pre-determined circumference. Thus, asfurther shown in FIGS. 5A-5J, any two of the differently-shapedhalf-shells can be joined together around a center brace to form aflattened elongate exhaust tube 10 having a constant and pre-determinedcircumference 16 which encloses a constant internal cross-sectional area18 along the length therefore. As racing standards on a particularcircuit may restrict all exhaust pipes to a maximum pre-determinedcircumference or less, this feature can be advantageous since the shapeof the modular exhaust tube can be changed or modified through selectionof the various differently-shaped half-shells without changing thecircumference of the exhaust tube.

Illustrated in FIGS. 6A and 6B is another representative embodiment 11of the modular exhaust tube system in which each of the sidewaysopenings 38 of elongate half shells 32, 34 can have at least oneinwardly-bending lip 50 (FIG. 6A), and wherein the inwardly-bending lipsof the coupled half-shells can join together around the center brace 60to form a groove 54 for containing weld melt 56 from a linear weld (FIG.6B). Having a groove for containing the weld melt from a linear weld canbe advantageous over the prior art, since the welded and fused materialfrom the three intersecting pieces (the lip from each half-shell and theedge of the center brace) can merge together into a homogenous jointthat is stronger and more stress-resistant than the spot-welded orlinear-welded joints used in the prior art to join two intersectingplates or abutting plates. Moreover, having a groove formed by twoinwardly bending lips 50 allows more of the weld melt 56 to remain aspart of the joint of the assembled exhaust tube after removal of anyexcess weld melt projecting above the surface of the exhaust tube duringa finish grinding stage. This can result in a larger joint that is morecapable of resisting the stress and corrosive forces found in a heatedexhaust gas environment.

In accordance with another representative embodiment, FIGS. 7A-9Billustrate exploded and assembled views of a modular exhaust tube system100 that can include a modular transition tube 150 or transition sectioncoupled to the inlet end 112 of a modular exhaust tube 110. Thetransition tube can operate to connect the secondary exhaust piping ofthe internal combustion engine to the flattened profile of the elongateexhaust tube, and to smoothly transition the round or oval shape of theexhaust outlet of the secondary exhaust piping to the differentsubstantially U-shaped cross-sectional profiles of the variousinterchangeable and modular half-shells 120.

As shown in FIGS. 7A and 7B, the transition tube 150 can include first172 and second 174 tapered half-shells 160, with each tapered half-shellcomprising a tapered thin-wall body 176 also having a substantiallyU-shaped cross-sectional profile, and with a tapered sideways 178opening along the length of the body. The tapered half-shells can besloped inward in the vertical plane and outward in the horizontal planeto accommodate the reduced height 144 and the increased width 146 of theexhaust tube 110, in relation to the height and width of a moresymmetrically-rounded secondary exhaust piping outlet. The transitiontube 150 can also include a center brace 180 having dimensions whichspan the length 192 and tapering height 194 of the tapered sidewaysopenings 178.

In a manner similar to the assembly of the exhaust tube 110 itself, thetapered sideways openings 178 of the first and second taperedhalf-shells 160 can be coupled together around the center brace 180 toform an enclosed transition tube 150 having a transition inlet 152shaped to match the rounded discharge piping and a transition outlet 154shaped to match the inlet end 112 of the elongate exhaust tube, as shownin FIG. 7B. The first and second tapered half-shells 160 can beassembled together to form a transition tube with a transition outlet154 that matches the shape of the assembled curved half-shells 120. Incontrast, the first and second tapered half-shells 168 of FIGS. 8A and8B can be assembled together form a transition tube 150 with atransition outlet 154 that matches the shape of the assembled peakedhalf-shells 128 of the exhaust tube 110. And as shown in FIGS. 9A and9B, the first and second tapered half-shells 164 of FIGS. 8A and 8B canbe assembled together form a transition tube 150 with a transitionoutlet 154 that matches the shape of the assembled trapezoid half-shells124 of the exhaust tube 110.

Therefore, it is understood that any of the tapered half-shells 172, 174that can be assembled into the transition tube 150 can be formed tomatch any of the different substantially U-shaped half-shells 132, 134of the exhaust tube 110, and can thus be configured to match any of thecross-sectional profiles of the exhaust tube illustrated in FIGS. 5A-5I.Furthermore, it is also to be understood that each of the taperedsideways openings can also have one or more inwardly-bending lips, asshown in FIGS. 6A-6B, and that the inwardly-bending lips of the coupledtapered half-shells can also join together around the tapered centerbrace of the transition tube 150 to form a groove that contains the weldmelt from a linear weld.

Referring back to FIGS. 7A and 8A, the tapered center brace 180 of thetransition section 150 can be separate from the center brace 140 of theelongate exhaust tube 100, and can include apertures 188 which may ormay not correspond with apertures 148 included in the center brace ofthe elongate exhaust tube 110. In another aspect of the presentinvention illustrated in FIG. 9A, however, the center brace 190 of theelongate exhaust tube 110 can comprise an extension 192 that serves asthe center brace for the transition tube 150. One advantage of theembodiment of FIGS. 9A and 9B is that both the elongate half-shells 132,134 of the exhaust tube 110 and the tapered half shells 172, 174 of thetransition tube can be coupled together around the same center brace 190to form an enclosed and flattened elongate exhaust tube 110 with apre-assembled tapered transition section 150 having a common brace or“backbone”. The resulting exhaust tube system with a unitary centerbrace can provide additional rigidity and strength over embodiments inwhich all components are assembled separately, while at the same timebeing fully customizable to accommodate the various combinations of theelongate 124 and tapered 164 half-shells described above.

It can be seen in FIG. 7A that the tapered center brace 180 can beasymmetrical with an inwardly tapered top edge and a straight bottomedge. This can be advantageous when accommodating secondary exhaustpiping from the internal combustion engine which has been configured tomaximize the ground clearance underneath the vehicle so that the bottomsurface of the elongate exhaust tube remains the lowest point on thevehicle. In another aspect of the present invention illustrated in FIGS.8A and 9A, however, the tapered center brace 180, 192 can be symmetricalwith both the top and bottom edges forced with an inward taper. Thisalternative configuration can be useful when accommodating a secondaryexhaust piping outlet that for one reason or another extends below thebottom of the elongate exhaust tube.

Illustrated in FIGS. 10A-10E and FIGS. 11A-11B are variousrepresentative embodiments of a modular exhaust tube system 300 that caninclude a tandem flattened elongate exhaust tube 360 positioned adjacentto but without contacting the first exhaust tube 340, for directingadditional exhaust gases from the internal combustion engine. As can beseen in FIGS. 11A and 11B, in some vehicle exhaust system it may bedesirable to direct the exhaust gases from both sides of the engine 320to the same side of the vehicle 310 that is opposite the fuel inletlocation, so as to reduce the risk of accidental fire in the case of afuel spill. Thus, both exhaust headers 322, 326 can connect withsecondary exhaust system piping 324, 228 having the standard, morerounded cross-sectional piping profiles. In turn, the outlet from thesecondary exhaust piping 324, 328 can be coupled to transition tubes350, 370 that can direct the hot exhaust gases into the tandem elongateexhaust tubes 340, 360 for discharge out the side of the vehicle. As theelongate exhaust tubes 340, 360 can be provided with longer lengthsrequired of most vehicle, each exhaust tube can be trimmed to lengthafter installation on the vehicle.

In certain instances racing standards on a particular circuit mayrequire that the exhaust system for each exhaust header be constructedand maintained separately, and with a uniform gap 330 between any twoelongate exhaust tubes 340, 360 directing exhaust gases to the same sideof the racing vehicle. However, it may also desirable for theowner/operator of the racing vehicle to keep the uniform gap as narrowas possible to conserve space under the vehicle and limit aerodynamicdrag, as two narrow bodies can usually generate more drag than one widebody. Therefore, as shown in FIGS. 10A-10E, the half-shells 342, 344,362, 264 of the first 340 and second 360 elongate exhaust tubes can beselected to have complementary sides for the elongate half-shells 344,362 that are adjacent to each other. As can be seen, the complementaryexposed sides can include complementary trapezoid half-shells (FIGS. 10Aand 10C), complementary rectangle half-shells (FIGS. 10B and 10D), andcomplementary sigma-peaked half-shells (FIG. 10E).

Also illustrated in FIGS. 10A-10E is the advantage provided by themodular exhaust tube system 300 of the present invention that allows theleading side surface 332 and/or trailing side surfaces 334 of theelongate exhaust tubes 340, 360 to be modified or adjusted by theowner/operator of the vehicle to affect the aerodynamics of the air flowunder the racing vehicle. Whereas the aerodynamic design of the leadingand trailing sides of the prior art exhaust systems is either limited tothe stock designs or is prohibitively difficult and expensive to modify,the leading 332 and trailing 334 surfaces of the elongate exhaust tubescan be easily and inexpensively adjusted in accordance with a user'sparticular preference. Furthermore, this benefit can apply to both theadjacent-exhaust tube configuration illustrated in FIGS. 11A-11B, aswell as to the separated-exhaust tube configuration shown in FIGS.12A-12B in which the exhaust gases from opposite sides of the engine 320are directed to the same opposite sides of the vehicle 310.

The foregoing detailed description describes the invention withreference to specific representative embodiments. However, it will beappreciated that various modifications and changes can be made withoutdeparting from the scope of the present invention as set forth in theappended claims. The detailed description and accompanying drawings areto be regarded as illustrative, rather than restrictive, and any suchmodifications or changes are intended to fall within the scope of thepresent invention as described and set forth herein.

More specifically, while illustrative representative embodiments of theinvention have been described herein, the present invention is notlimited to these embodiments, but includes any and all embodimentshaving modifications, omissions, combinations (e.g., of aspects acrossvarious embodiments), adaptations and/or alterations as would beappreciated by those skilled in the art based on the foregoing detaileddescription. The limitations in the claims are to be interpreted broadlybased on the language employed in the claims and not limited to examplesdescribed in the foregoing detailed description or during theprosecution of the application, which examples are to be construed asnon-exclusive. For example, any steps recited in any method or processclaims, furthermore, may be executed in any order and are not limited tothe order presented in the claims. The term “preferably” is alsonon-exclusive where it is intended to mean “preferably, but not limitedto.” Accordingly, the scope of the invention should be determined solelyby the appended claims and their legal equivalents, rather than by thedescriptions and examples given above.

1. A modular exhaust tube system for directing exhaust gases from aninternal combustion engine, comprising: first and second elongatehalf-shells, each half-shell comprising an elongate thin-wall bodyhaving a substantially U-shaped cross-sectional profile with a pair ofsubstantially straight parallel legs and a constant sideways openingalong the length of the body, said half-shells having a half-shellheight between the outside edges of said legs along said sidewaysopening; and a center brace having dimensions which span the length andheight of the sideways openings and which height dimension issubstantially equal to the half-shell height; wherein the sidewaysopenings of the first and second half-shells are coupled togetheragainst the center brace to form a flattened elongate exhaust tubehaving an inlet end and an outlet end for directing exhaust gases froman internal combustion engine.
 2. The exhaust tube system of claim 1,wherein the first and second elongate half-shells are reversibletop-to-bottom and end-to-end.
 3. A modular exhaust tube system fordirecting exhaust gases from an internal combustion engine, comprising:first and second elongate half-shells, each half-shell comprising anelongate thin-wall body having a substantially U-shaped cross-sectionalprofile with a constant sideways opening along the length of the body;and a center brace having dimensions which span the length and height ofthe sideways openings; wherein the sideways openings of the first andsecond half-shells are coupled together around the center brace to forma flattened elongate exhaust tube having an inlet end and an outlet endfor directing exhaust gases from an internal combustion engine; andwherein the first and second elongate half-shells are selected from agroup of interchangeable and modular half-shells having differentsubstantially U-shaped cross-sectional profiles.
 4. The exhaust tubesystem of claim 3, wherein the exhaust tube formed from any twohalf-shells selected from the group of interchangeable and modularhalf-shells has a predetermined circumference and a constant internalcross-sectional area from the inlet end to the outlet end.
 5. Theexhaust tube system of claim 3, wherein the different substantiallyU-shaped cross-sectional profiles are selected from a group consistingof a rounded-shaped profile, a rectangle-shaped profile, atrapezoid-shaped profile, a sigma-shaped profile and a peaked-shapedprofile.
 6. The exhaust tube system of claim 1, wherein the center braceis solid along the length thereof to restrict the exhaust gases frompassing from one half-shell to the other half-shell.
 7. The exhaust tubesystem of claim 1, wherein the center brace comprises a plurality ofapertures along a length thereof for allowing the exhaust gases to passfrom one half-shell to the other half-shell.
 8. The exhaust tube systemof claim 7, wherein the shape of the plurality of apertures is selectedfrom the group consisting of round, NACA, oblong, triangular, polygonal,and rounded slot shapes, and combinations thereof.
 9. The exhaust tubesystem of claim 1, further comprising each of the sideways openingshaving at least one inwardly-bending lip, and wherein theinwardly-bending lips of coupled half-shells join together around thecenter brace to form a groove for containing weld melt from a linearweld.
 10. A modular exhaust tube system for directing exhaust gases froman internal combustion engine, comprising: first and second elongatehalf-shells, each half-shell comprising an elongate thin-wall bodyhaving a substantially U-shaped cross-sectional profile with a constantsideways opening along the length of the body; and a center brace havingdimensions which span the length and height of the sideways openings;wherein the sideways openings of the first and second half-shells arecoupled together around the center brace to form a flattened elongateexhaust tube having an inlet end and an outlet end for directing exhaustgases from an internal combustion engine; and further comprising atandem flattened elongate exhaust tube positioned adjacent to butwithout contacting the exhaust tube for directing additional exhaustgases from the internal combustion engine.
 11. The exhaust tube systemof claim 1, further comprising a transition tube for coupling the inletend of the exhaust tube system to a rounded secondary exhaust pipingoutlet of the internal combustion engine, said transition tubecomprising: first and second tapered half-shells, each taperedhalf-shell comprising a tapered thin-wall body having a substantiallyU-shaped cross-sectional profile with a tapered sideways opening alongthe length of the body; and a tapered center brace having dimensionswhich span the length and height of the tapered sideways openings,wherein the tapered sideways openings of the first and second taperedhalf-shells are coupled together around the center brace to form anenclosed transition tube having a transition inlet shaped to match therounded secondary exhaust piping outlet and a transition outlet shapedto match the inlet end of the elongated exhaust tube.
 12. The exhausttube system of claim 11, wherein the transition inlet shape comprises around shape or an oval shape.
 13. The exhaust tube system of claim 11,wherein the tapered center brace is separate from the center brace ofthe elongate exhaust tube.
 14. The exhaust tube system of claim 11,wherein the tapered center brace is a continuous extension of the centerbrace of the elongate exhaust tube.
 15. The exhaust tube system of claim11, wherein the tapered center brace is asymmetrical having a taperedtop edge and a straight bottom edge.
 16. The exhaust tube system ofclaim 11, further comprising each of the tapered sideways openingshaving at least one inwardly-bending lip, and wherein theinwardly-bending lips of coupled tapered half-shells join togetheraround the tapered center brace to form a groove for containing weldmelt from a linear weld.
 17. A method for making an exhaust tube for aninternal combustion engine, comprising: obtaining a first and secondelongate half-shell, each half-shell comprising an elongate thin-wallbody having a substantially U-shaped cross-sectional profile with aconstant sideways opening along the length of the body; obtaining acenter brace having dimensions which span the length and height of thesideways openings, wherein the center brace is selected from a group ofinterchangeable and modular center braces consisting of a solid centerbrace and center braces having a different plurality of shapedapertures, aligning the sideways openings of the first and secondhalf-shells together around the center brace; and coupling thehalf-shells and the center brace together to form a flattened elongateexhaust tube having an inlet end and an outlet end for directing exhaustgases from an internal combustion engine.
 18. The method of claim 17,further comprising selecting the first and second elongate half-shellsfrom a group of interchangeable and modular half-shells having differentsubstantially U-shaped cross-sectional profiles.
 19. The method of claim18, wherein the different substantially U-shaped cross-sectionalprofiles are selected from a group consisting of a rectangle-shapedprofile, an oval-shaped profile, a trapezoid-shaped profile and asigma-shaped profile.
 20. The method of claim 17, wherein the first andsecond elongate half-shells are reversible top-to-bottom and end-to-end.21. The method of claim 17, wherein the different plurality of shapedapertures are selected from the group consisting of a round shape, aNACA shape, a triangular shape, a polygonal shape, an oblong shape and aslotted rectangular shape, and combinations thereof.
 22. The method ofclaim 17, wherein coupling the first and second elongate half-shells andthe center brace together further comprises welding the half-shells andthe center brace together using a linear weld.
 23. The method of claim22, wherein obtaining a first and second elongate half-shells furthercomprises obtaining half-shells with sideways openings having at leastone inwardly-bending lip, and wherein the inwardly-bending lips of thecoupled half-shells join together around the center brace to form agroove for containing weld melt from the linear weld.
 24. The method ofclaim 17, further comprising positioning a tandem flattened elongateexhaust tube adjacent to but without contacting the exhaust tube fordirecting additional exhaust gases from the internal combustion engine.